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  <title>获取指定加密算法的密钥大小</title>
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<div id="layout">
  <div id="layout-content"><div id="function.mcrypt-get-key-size" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">mcrypt_get_key_size</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7 &lt; 7.2.0, PECL mcrypt &gt;= 1.0.0)</p><p class="refpurpose"><span class="refname">mcrypt_get_key_size</span> &mdash; <span class="dc-title">获取指定加密算法的密钥大小</span></p>

 </div>
 <div id="function.mcrypt-get-key-size-refsynopsisdiv">
  <div class="warning"><strong class="warning">警告</strong><p class="simpara">本函数已自 PHP 7.1.0 起<em class="emphasis">废弃</em>并将自
PHP 7.2.0 起<em class="emphasis">移除</em>。强烈建议不要使用本函数。</p></div>
 </div>
 <div class="refsect1 description" id="refsect1-function.mcrypt-get-key-size-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>mcrypt_get_key_size</strong></span>(<span class="methodparam"><span class="type">int</span> <code class="parameter">$cipher</code></span>): <span class="type"><span class="type">int</span>|<span class="type"><span class="type false">false</span></span></span></div>

  <div class="methodsynopsis dc-description"><span class="methodname"><strong>mcrypt_get_key_size</strong></span>(<span class="methodparam"><span class="type">string</span> <code class="parameter">$cipher</code></span>, <span class="methodparam"><span class="type">string</span> <code class="parameter">$mode</code></span>): <span class="type"><span class="type">int</span>|<span class="type"><span class="type false">false</span></span></span></div>

  <p class="para rdfs-comment">
   第一个原型是针对 libmcrypt 2.2.x 的，
   第二个原型是针对 libmcrypt 2.4.x 或 2.5.x 的。
  </p>
  <p class="para">
   <span class="function"><strong>mcrypt_get_key_size()</strong></span> 用来获取
   由 <code class="parameter">cipher</code> 
   所指定的算法和模式所需的密钥长度。
  </p>
  <p class="para">
   <span class="function"><a href="function.mcrypt-enc-get-key-size.html" class="function">mcrypt_enc_get_key_size()</a></span> 更加有用，
   因为它使用由 <span class="function"><a href="function.mcrypt-module-open.html" class="function">mcrypt_module_open()</a></span> 返回的资源。
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-function.mcrypt-get-key-size-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt>
<code class="parameter">cipher</code></dt>

     <dd>

      <p class="para"><strong><code>MCRYPT_ciphername</code></strong> 常量中的一个，或者是字符串值的算法名称。</p>
     </dd>

    
    
     <dt>
<code class="parameter">mode</code></dt>

     <dd>

      <p class="para"><strong><code>MCRYPT_MODE_modename</code></strong> 常量中的一个，或以下字符串中的一个：&quot;ecb&quot;，&quot;cbc&quot;，&quot;cfb&quot;，&quot;ofb&quot;，&quot;nofb&quot; 和 &quot;stream&quot;。</p>
     </dd>

    
   </dl>

  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.mcrypt-get-key-size-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   返回算法所支持的最大密钥大小，以字节为单位。
    或者在失败时返回 <strong><code>false</code></strong>。
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-function.mcrypt-get-key-size-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-914">
    <p><strong>示例 #1 <span class="function"><strong>mcrypt_get_key_size()</strong></span> 例程</strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #007700">echo&nbsp;</span><span style="color: #0000BB">mcrypt_get_key_size</span><span style="color: #007700">(</span><span style="color: #DD0000">'tripledes'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'ecb'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</code></div>
    </div>

    <div class="example-contents"><p>
     在 libmcrypt 2.4.x 或 2.5.x 版本中，
     如果使用本函数。
    </p></div>
    <div class="example-contents"><p>以上例程会输出：</p></div>
    <div class="example-contents screen">
<div class="cdata"><pre>
24
</pre></div>
    </div>
   </div>   
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.mcrypt-get-key-size-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="function.mcrypt-get-block-size.html" class="function" rel="rdfs-seeAlso">mcrypt_get_block_size()</a> - 获得加密算法的分组大小</span></li>
    <li class="member"><span class="function"><a href="function.mcrypt-enc-get-key-size.html" class="function" rel="rdfs-seeAlso">mcrypt_enc_get_key_size()</a> - 返回打开的模式所能支持的最长密钥</span></li>
    <li class="member"><span class="function"><a href="function.mcrypt-encrypt.html" class="function" rel="rdfs-seeAlso">mcrypt_encrypt()</a> - 使用给定参数加密明文</span></li>
   </ul>
  </p>
 </div>


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